Gold(I)-Catalyzed [8+4] Cycloaddition of 1,4-All-Carbon Dipoles with Tropone

Abstract

Herein, we describe a gold(I)-catalyzed generation of nonclassical gold-containing 1,4-all-carbon dipoles from cycloisomerization/1,2carbene transfer/ring opening cascade reactions of readily accessible allenyl ketones bearing a cyclopropyl moiety and its cyclization with tropone. This method features an unprecedented formal [8+4] high-order cycloaddition under mild conditions for delivering structurally complex 7,7,5-tricycles in generally moderate to high yields.

High-order dipolar annulations with metal-containing reactive dipoles

“…In the same year, Miao and Ren disclosed (4+8) annulations of tropone 206 with allenyl ketones 196 under Au( i ) catalysis (Scheme 46). 100 This HODA involving an in situ generated 1,4-dipole intermediate ( TS-7 ) provides a variety of 7,7,5-fused tricyclic products 3 in generally moderate to good yields and with complete selectivity under room temperature (rt).…”

Synthesis of Substituted Tropones and Advancement for the Construction of Structurally Significant Skeletons

“…In 2020, Maozhong Miao, Hongjun Ren, and co‐workers developed the [8+4] cycloaddition of tropone 77 catalyzed by Gold(I) to produce moderate to high yields of 7,7,5‐fused tricycles 79 (Scheme 15) (Table 2). [83] The reaction conditions were optimized using tropone 34 and cyclopropyl‐tethered allenyl ketone 78 a as model substrates and it was noted that 6.0 mol% of t ‐BuXPhosAuCl as the catalyst, 5.0 mol% of AgSbF 6 as additive with DCM as solvent afforded the cycloadduct 79 a with a yield of 73 %. This methodology has broad substrate scope and under optimized conditions, a large number of substrates provided the corresponding cycloadduct.…”

1,2-Migrations onto Gold Carbene Centers

“…After that, 1,2-alkyl migration occurs to form a furan-fused cyclobutene 59 , which then undergoes a variety of transformations. Ren and co-workers developed a series of reactions for the synthesis of polysubstituted furans based on this chemistry. − For example, in 2018, they reported the synthesis of tri- or tetrasubstituted furans 60 via the gold­(I)-catalyzed cascade cycloisomerization/ring-opening reaction of allenyl ketones bearing a cyclopropyl moiety with a wide variety of alcohols or ketones (Scheme ). When cyclopentyl-substituted allenyl ketone 61 was subjected to the standard conditions, a six-membered-ring-fused furan 62 was obtained in 66% yield.…”